AbstractRoutingDataSource源码分析

AbstractRoutingDataSource源码：

/* * Copyright 2002-2012 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.springframework.jdbc.datasource.lookup;...../** * Abstract {@link javax.sql.DataSource} implementation that routes {@link #getConnection()} * calls to one of various target DataSources based on a lookup key. The latter is usually * (but not necessarily) determined through some thread-bound transaction context. * * @author Juergen Hoeller * @since 2.0.1 * @see #setTargetDataSources * @see #setDefaultTargetDataSource * @see #determineCurrentLookupKey() */public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {   private Map<Object, Object> targetDataSources;   private Object defaultTargetDataSource;   private boolean lenientFallback = true;   private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();   private Map<Object, DataSource> resolvedDataSources;   private DataSource resolvedDefaultDataSource;   /**    * Specify the map of target DataSources, with the lookup key as key.    * The mapped value can either be a corresponding {@link javax.sql.DataSource}    * instance or a data source name String (to be resolved via a    * {@link #setDataSourceLookup DataSourceLookup}).    * <p>The key can be of arbitrary type; this class implements the    * generic lookup process only. The concrete key representation will    * be handled by {@link #resolveSpecifiedLookupKey(Object)} and    * {@link #determineCurrentLookupKey()}.    */   public void setTargetDataSources(Map<Object, Object> targetDataSources) {      this.targetDataSources = targetDataSources;   }   /**    * Specify the default target DataSource, if any.    * <p>The mapped value can either be a corresponding {@link javax.sql.DataSource}    * instance or a data source name String (to be resolved via a    * {@link #setDataSourceLookup DataSourceLookup}).    * <p>This DataSource will be used as target if none of the keyed    * {@link #setTargetDataSources targetDataSources} match the    * {@link #determineCurrentLookupKey()} current lookup key.    */   public void setDefaultTargetDataSource(Object defaultTargetDataSource) {      this.defaultTargetDataSource = defaultTargetDataSource;   }   /**    * Specify whether to apply a lenient fallback to the default DataSource    * if no specific DataSource could be found for the current lookup key.    * <p>Default is "true", accepting lookup keys without a corresponding entry    * in the target DataSource map - simply falling back to the default DataSource    * in that case.    * <p>Switch this flag to "false" if you would prefer the fallback to only apply    * if the lookup key was {@code null}. Lookup keys without a DataSource    * entry will then lead to an IllegalStateException.    * @see #setTargetDataSources    * @see #setDefaultTargetDataSource    * @see #determineCurrentLookupKey()    */   public void setLenientFallback(boolean lenientFallback) {      this.lenientFallback = lenientFallback;   }   /**    * Set the DataSourceLookup implementation to use for resolving data source    * name Strings in the {@link #setTargetDataSources targetDataSources} map.    * <p>Default is a {@link JndiDataSourceLookup}, allowing the JNDI names    * of application server DataSources to be specified directly.    */   public void setDataSourceLookup(DataSourceLookup dataSourceLookup) {      this.dataSourceLookup = (dataSourceLookup != null ? dataSourceLookup : new JndiDataSourceLookup());   }   @Override   public void afterPropertiesSet() {      if (this.targetDataSources == null) {         throw new IllegalArgumentException("Property 'targetDataSources' is required");      }      this.resolvedDataSources = new HashMap<Object, DataSource>(this.targetDataSources.size());      for (Map.Entry<Object, Object> entry : this.targetDataSources.entrySet()) {         Object lookupKey = resolveSpecifiedLookupKey(entry.getKey());         DataSource dataSource = resolveSpecifiedDataSource(entry.getValue());         this.resolvedDataSources.put(lookupKey, dataSource);      }      if (this.defaultTargetDataSource != null) {         this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);      }   }   /**    * Resolve the given lookup key object, as specified in the    * {@link #setTargetDataSources targetDataSources} map, into    * the actual lookup key to be used for matching with the    * {@link #determineCurrentLookupKey() current lookup key}.    * <p>The default implementation simply returns the given key as-is.    * @param lookupKey the lookup key object as specified by the user    * @return the lookup key as needed for matching    */   protected Object resolveSpecifiedLookupKey(Object lookupKey) {      return lookupKey;   }   /**    * Resolve the specified data source object into a DataSource instance.    * <p>The default implementation handles DataSource instances and data source    * names (to be resolved via a {@link #setDataSourceLookup DataSourceLookup}).    * @param dataSource the data source value object as specified in the    * {@link #setTargetDataSources targetDataSources} map    * @return the resolved DataSource (never {@code null})    * @throws IllegalArgumentException in case of an unsupported value type    */   protected DataSource resolveSpecifiedDataSource(Object dataSource) throws IllegalArgumentException {      if (dataSource instanceof DataSource) {         return (DataSource) dataSource;      }      else if (dataSource instanceof String) {         return this.dataSourceLookup.getDataSource((String) dataSource);      }      else {         throw new IllegalArgumentException(               "Illegal data source value - only [javax.sql.DataSource] and String supported: " + dataSource);      }   }   @Override   public Connection getConnection() throws SQLException {      return determineTargetDataSource().getConnection();   }   @Override   public Connection getConnection(String username, String password) throws SQLException {      return determineTargetDataSource().getConnection(username, password);   }   @Override   @SuppressWarnings("unchecked")   public <T> T unwrap(Class<T> iface) throws SQLException {      if (iface.isInstance(this)) {         return (T) this;      }      return determineTargetDataSource().unwrap(iface);   }   @Override   public boolean isWrapperFor(Class<?> iface) throws SQLException {      return (iface.isInstance(this) || determineTargetDataSource().isWrapperFor(iface));   }   /**    * Retrieve the current target DataSource. Determines the    * {@link #determineCurrentLookupKey() current lookup key}, performs    * a lookup in the {@link #setTargetDataSources targetDataSources} map,    * falls back to the specified    * {@link #setDefaultTargetDataSource default target DataSource} if necessary.    * @see #determineCurrentLookupKey()    */   protected DataSource determineTargetDataSource() {      Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");      Object lookupKey = determineCurrentLookupKey();      DataSource dataSource = this.resolvedDataSources.get(lookupKey);      if (dataSource == null && (this.lenientFallback || lookupKey == null)) {         dataSource = this.resolvedDefaultDataSource;      }      if (dataSource == null) {         throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");      }      return dataSource;   }   /**    * Determine the current lookup key. This will typically be    * implemented to check a thread-bound transaction context.    * <p>Allows for arbitrary keys. The returned key needs    * to match the stored lookup key type, as resolved by the    * {@link #resolveSpecifiedLookupKey} method.    */   protected abstract Object determineCurrentLookupKey();}

其中的targetDataSource

 Map<Object, Object> targetDataSources

在配置文件中配置dataSource时，设置targetDataSources

<bean id="dataSource" class="com.taotao.manage.datasource.DynamicDataSource">   <property name="targetDataSources">      <map key-type="java.lang.String">         <entry key="master" value-ref="masterDataSource"/>         <entry key="slave1" value-ref="slave1DataSource"/>      </map>   </property>   <property name="defaultTargetDataSource" ref="masterDataSource"/></bean>

根据targetDataSources可以在afterPropertiesSet方法中对targetDataSources进行解析，获取真正的datasources

@Overridepublic void afterPropertiesSet() {   if (this.targetDataSources == null) {      throw new IllegalArgumentException("Property 'targetDataSources' is required");   }   this.resolvedDataSources = new HashMap<Object, DataSource>(this.targetDataSources.size());   for (Map.Entry<Object, Object> entry : this.targetDataSources.entrySet()) {      Object lookupKey = resolveSpecifiedLookupKey(entry.getKey());      DataSource dataSource = resolveSpecifiedDataSource(entry.getValue());      this.resolvedDataSources.put(lookupKey, dataSource);   }   if (this.defaultTargetDataSource != null) {      this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);   }}